Presently, a patch of skin is excised from the rear area of a scalp and the scalp is then sutured. This patch is then dissected under a microscope and hair follicular units are isolated. The process is slow, tedious, exacting and expensive. It would be advantageous to develop a hair graft harvesting technique which would permit the removal of individual hair grafts from a harvesting area of a scalp or hair bearing skin. Not only would such a technique expedite hair graft harvesting and reduce cost, it also would eliminate the surgical procedure of excising a patch of skin and the attending suturing.
But the harvesting of individual hair follicular units or grafts has its own problems:
U.S. Pat. No. 6,572,625 demonstrates a mechanism for alignment of hair follicles within a follicular unit so that the follicular unit can be extracted, one follicular unit (FU) at a time. U.S. Pat. No. 6,572,625 sets up a situation where a hollow punch with a sharp or dull cutting edge can be used to remove the follicular unit with reduced damage of cutting or amputating the follicles in the FU with perfect alignment. When a punch is introduced to surround the FU, the hollow tube gathers the hair follicles as it is advanced deeper into the scalp or hair bearing skin (a distance of about 5-7 mm).
The anatomy of a follicular unit is not cylindrical in its normal undisturbed state, in vivo. The hairs of the FU grow in groups of one, two, threes, and four hairs. The hairs of the FU exit at the skin surface in close proximity to one another. However, the hairs of the FU sometimes diverge and cone out in the dermal and fatty layer beneath the skin. Hairs of the FU have a maximal divergence at the location of the bulb.
The hair follicles are connected to stroma (collagen fibrils) which forms a lattice work of supporting structures, forming a framework holding the hair follicles in place and connecting the hair follicles to the surrounding fat and blood vessels. This fibrous framework is made up of collagen and the nature of the collagen varies from person to person. Some collagen fibrils are elastic and some inelastic. These inherent characteristics of the FU make the extraction of the FU uniquely variable on an individual basis.
In some people, the amount of elastic fibrils is disproportionably high in number, while in other individuals they it is disproportionably low in numbers. During the coring of an FU, it is theorized that if the number of elastic fibrils is high, the hollow punch easily ‘gathers’ the hair follicles as it is advanced into the deeper fat, probably tearing at the supporting stroma and breaking it apart. In those with a high elastic content, the cutting or breaking of these elastic fibrils occurs easily as the hair follicles advance into the descending hollow punch.
In some people, however, the elastic fibrils are few in number and the inelastic fibrils are high so that the hair and the surrounding structures do not easily cut or tear as the hollow punch is advanced. When this happens, the point of greatest weakness may be the hair shafts and the hair shaft is either cut or torn apart, damaging the FU as attempts are made to remove it.
The extraction of the follicular unit is a mechanical process and it is heavily influenced by mechanical factors related to the stroma that support each and every hair follicle. The results of these anatomical variations make extraction of each hair follicle variable on an individual and even local (different areas of the skin) basis. Variations in successful extraction of hairs within an FU often produce unacceptable variation in the success of FU Extraction.